Convolutional Neural Network (Single Layer, Large)

Author: Jie Wang (jiewang@cs.ucla.edu)

This is an example of large-size matrix multiplication. The design files can be found at ${AUTOSA_ROOT}/autosa_tests/large/cnn. The testing environment is summarized in the table below.

Target FPGA	Xilinx Alveo U250
FPGA Synthesis Tools	Xilinx Vivado HLS 2019.2, Xilinx Vitis 2019.2
CPU	Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz

C Simulation

Run the following example command to generate one design with HLS host code.

./autosa ./autosa_tests/large/cnn/kernel.c \
--config=./autosa_config/autosa_config.json \
--target=autosa_hls_c \
--output-dir=./autosa.tmp/output \
--sa-sizes="{kernel[]->space_time[4];kernel[]->array_part[64,56,14,64];kernel[]->latency[4,4,7];kernel[]->simd[1,1,8]}" \
--simd-info=./autosa_tests/large/cnn/simd_info.json \
--host-serialize \
--no-reverse-order \
--hls

After compilation, you will find all generated files under the directory ${AUTOSA_ROOT}/autosa.tmp/output/src. Copy the hls_script.tcl to the directory autosa.tmp/output.

cp ${AUTOSA_ROOT}/autosa_tests/large/cnn/hls_script.tcl ${AUTOSA_ROOT}/autosa.tmp/output/

Run the TCL script to perform C simulation.

cd ${AUTOSA_ROOT}/autosa.tmp/output/
vivado_hls -f hls_script.tcl

You should see Passed printed out in your terminal showing that C simulation is performed successfully.

Bitstream Generation

If you need to generate the bitstream for on-board testing, simply remove the --hls flag from the previous AutoSA command.

./autosa ./autosa_tests/large/cnn/kernel.c \
--config=./autosa_config/autosa_config.json \
--target=autosa_hls_c \
--output-dir=./autosa.tmp/output \
--sa-sizes="{kernel[]->space_time[4];kernel[]->array_part[64,56,14,64];kernel[]->latency[4,4,7];kernel[]->simd[1,1,8]}" \
--simd-info=./autosa_tests/large/cnn/simd_info.json \
--no-reverse-order \
--host-serialize

Now instead of HLS host code, an OpenCL host code is generated.

We have prepared a template Makefile for Xilinx Vitis tools.

cp ${AUTOSA_ROOT}/autosa_tests/large/cnn/Makefile ${AUTOSA_ROOT}/autosa.tmp/output/
cp ${AUTOSA_ROOT}/autosa_tests/large/cnn/connectivity.cfg ${AUTOSA_ROOT}/autosa.tmp/output/

To generate the bitstream, use the following command.

make all

After the bitstream is generated, use the following command to run it on-board.

make check

Note

As this design is rather large, Vitis fails to successfully route the design on-board in our experiment. We will rely on AutoBridge to route this design.

Using AutoBridge to Boost Frequency

You may also try to use AutoBridge to boost the design frequency. We cover how to use AutoBridge to improve the frequency in Leveraging AutoBridge to Boost the Design Frequency.

The reference AutoBridge scripts used for this example can be found at ${AUTOSA_ROOT}/autosa_tests/large/cnn.

The tables below show the detailed comparison results between the original design (unoptimized) and the design optimized with AutoBridge (optimized).

Designs	MHz	LUT	REG	BRAM	DSP
Unoptimized	N/A	N/A	N/A	N/A	N/A
Optimized	265	884520 (57.93%)	1445020 (46.05%)	697 (29.84%)	8960 (72.99%)

Designs	Kernel Time (s)	Host Time (s)	GFLOPs
Unoptimized	N/A	N/A	N/A
Optimized	0.015865	0.188105	932.714